this project involves study of the alteration of metal sulfide minerals such as pyrite and galena. This represents an important environmental problem because it leads to generation of very low pH, metal-rich solutions that contaminate water supplies in the US and abroad. This work involves application of surface sensitive techniques to characterize the changes in structure and chemistry of the interface between the solid and solution. We are conducting a variety of experiments that measure the dissolution rates and need to verify that the surfaces of cleaved samples are not coated by submicron-sized particles. Through use of other microscopies (reflection differential interference contrast and scanning tunneling) we can observe the form and distribution of surface features at micron to centimeter scales or at few tens of nanometer to sub-angstrom scales. We believe that the high-resolution scanning electron microscope at the IMR provides a method to bridge these scales of observation in order to establish the general nature of the smaller scale measurements.